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Texas Instruments LM5161PWPT
- Part No.:
- LM5161PWPT
- Manufacturer:
- Texas Instruments
- Package:
- 14-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM5161PWPT.pdf
- Description:
- IC REG BCK FLYBACK ADJ 14HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:7,121
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Product details
Overview
LM5161PWPT from Texas Instruments is a 100-V, 1-A synchronous buck/Fly-Buck™ converter with integrated high-side and low-side MOSFETs, constant ON-time control, ±1% feedback reference, and FPWM-selectable CCM/DCM operation. It delivers regulated DC-DC conversion for industrial PLCs, IGBT gate drive bias, and isolated telecom secondary supplies.
For engineers reviewing the LM5161PWPT datasheet, LM5161PWPT pinout, LM5161PWPT application, or LM5161PWPT equivalent, key selection criteria include its 4.5–100 V input range, 1-A load capability, HTSSOP-14 package with exposed pad, FPWM-controlled conduction mode, and Fly-Buck™ topology support without external ripple injection.
Technical Context
The LM5161PWPT implements constant ON-time control with VIN-inversely proportional on-time, enabling stable switching frequency (up to 1 MHz) and eliminating need for external loop compensation. Its integrated 0.58 Ω high-side and 0.24 Ω low-side MOSFETs support synchronous rectification and eliminate external Schottky diode requirements.
FPWM pin enables mode selection: grounding selects DCM for light-load efficiency, while connecting to VCC forces CCM for multi-output Fly-Buck™ operation. Peak current limiting uses VIN- and VFB-dependent off-time, providing short-circuit protection with minimal foldback across –40°C to 125°C junction temperature.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 100 V - supports direct connection to 24 V industrial, 48 V telecom, and PoE rails without pre-regulation. |
| Output Current | 1 A maximum - sufficient for IGBT gate drivers, PLC I/O modules, and low-power isolated bias rails. |
| Feedback Reference | 2.0 V ±1% - enables precise output regulation (e.g., 3.3 V, 5 V, 12 V) using standard resistor dividers. |
| Switching Frequency | Adjustable up to 1 MHz - set via RON resistor; maintains near-constant frequency across line/load variations. |
| Thermal Protection | 175°C shutdown with 20°C hysteresis - prevents permanent damage during overload or poor PCB thermal design. |
| Soft-Start | Programmable via SS capacitor - controls output rise time and limits inrush current during power-up. |
| UVLO Threshold | 1.24 V (EN/UVLO pin) with adjustable hysteresis - ensures clean start-up and prevents brownout oscillation. |
Pinout & Package
LM5161PWPT is housed in a 14-pin HTSSOP package (5.00 mm × 4.40 mm) with exposed thermal pad (EP) connected to AGND for enhanced power dissipation. The package supports surface-mount assembly and requires controlled thermal land pattern per TI's layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AGND (Pin 1) | Analog ground reference | Return path for internal control circuitry; must be tied to quiet analog ground plane, separate from PGND at single point. |
| PGND (Pin 2) | Power ground return | Source node for low-side FET; carries high di/dt switch currents - requires low-inductance connection to power ground plane. |
| VIN (Pin 3) | Main input supply | Accepts 4.5–100 V DC; requires local ceramic input capacitor (≥10 µF) placed close to VIN and PGND pins. |
| EN/UVLO (Pin 4) | Enable and UVLO input | Logic-enable function with precision 1.24 V threshold; resistor divider from VIN allows programmable input undervoltage lockout. |
| RON (Pin 5) | ON-time programming | Resistor to VIN sets minimum on-time; determines switching frequency - e.g., 100 kΩ yields ~540 ns at 48 V. |
| SS (Pin 6) | Soft-start control | Capacitor to AGND sets ramp time; 1 nF minimum required for stability and monotonic startup. |
| NC (Pin 7) | No connection | Not internally bonded; must remain unconnected and unpopulated on PCB. |
| FPWM (Pin 8) | Forced PWM mode select | Ground = DCM for light-load efficiency; VCC = forced CCM for Fly-Buck™ multi-output or isolated designs. |
| FB (Pin 9) | Feedback input | Compares output voltage (via resistor divider) to 2.0 V reference; regulates output within ±1% over temp and line. |
| VCC (Pin 10) | Bias regulator output | 7.3 V internal LDO output; powers gate drivers and logic; can be externally biased (9–13 V) to reduce IC power loss at high VIN. |
| BST (Pin 11) | Bootstrap capacitor node | Connects to SW via 0.1 µF ceramic capacitor; provides gate drive voltage for high-side N-channel FET. |
| SW (Pins 12,13) | Switch node | Drain of high-side FET / source of low-side FET; connects to inductor and bootstrap capacitor; high dv/dt node requiring tight layout. |
| NC (Pin 14) | No connection | Not internally bonded; must remain unconnected and unpopulated on PCB. |
| EP | Exposed thermal pad | Internally connected to AGND; must be soldered to large copper thermal pad on PCB for RθJA = 39.3°C/W performance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated dual MOSFETs | Eliminates external high-side switch and Schottky diode - reduces BOM count and board area in buck and Fly-Buck™ topologies. |
| Constant ON-time control | Enables fast transient response and removes need for external compensation network - simplifies design for wide input/output ratios. |
| FPWM-selectable conduction mode | DCM improves light-load efficiency; CCM enables stable multi-output isolation - one IC supports both buck and Fly-Buck™ applications. |
| No external ripple injection | DCM operation achieves tight output regulation without adding ripple to FB node - avoids noise coupling and component count increase. |
| Prebias start-up | Allows safe startup into precharged output capacitors - prevents reverse current flow and protects downstream loads in hot-swap systems. |
Applications
| Industrial PLC Power Supply | IGBT Gate Drive Bias |
|---|---|
Use Scenario: Providing isolated 15-V/–5-V bias rails for high-voltage IGBT half-bridge drivers in motor drives and inverters. IC Role / Device Role / Timing Role: Fly-Buck™ controller generating dual-polarity, isolated outputs from a single 48-V bus. Use Value: Eliminates need for optocouplers or auxiliary windings; achieves <±1% regulation on secondary side without feedback transformer. | Use Scenario: Generating tightly regulated 12-V gate drive supply for SiC MOSFETs in EV charging stations operating from 800-V DC bus. IC Role / Device Role / Timing Role: High-input-voltage buck converter delivering low-noise, fast-transient 12-V rail directly from intermediate bus. Use Value: Integrated 100-V switches withstand transients; constant ON-time control ensures stable gate drive under dynamic load steps. |
| Telecom Primary-Side Bias | E-Meter PLC Interface |
Use Scenario: Powering control circuitry and ADCs on primary side of isolated DC-DC converters in 48-V telecom rectifiers. IC Role / Device Role / Timing Role: Primary-side buck regulator supplying 3.3-V/5-V rails with high PSRR and low EMI due to fixed-frequency CCM operation. Use Value: FPWM = VCC enables forced CCM - minimizes output voltage ripple critical for sensitive analog measurement circuits. | Use Scenario: Providing isolated 5-V bias for PLC modem ICs in smart electricity meters interfacing with 230-V AC power lines. IC Role / Device Role / Timing Role: Fly-Buck™ converter delivering reinforced-isolation 5-V output from meter's internal 12-V rail. Use Value: No external ripple circuit needed in DCM mode - meets IEC 61000-4-5 surge immunity requirements without added components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck/Fly-Buck™ converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5160PWPR | Same architecture but 65-V max input; lower RDS(ON) (0.45 Ω HS / 0.18 Ω LS); no FPWM pin - fixed DCM only. | Limited to ≤65 V inputs; cannot support Fly-Buck™ CCM mode or 100-V industrial transients. | Select when input stays below 65 V and Fly-Buck™ multi-output is not required - lower conduction loss at light loads. |
| LM5017MMX/NOPB | 75-V input, 600-mA output; requires external high-side FET; no integrated low-side switch; no FPWM control. | Lower current rating; higher BOM cost and layout complexity; no DCM/CCM selection - unsuitable for 1-A Fly-Buck™ designs. | Choose only for space-constrained 600-mA applications where external FET flexibility outweighs integration benefits. |
Compared with LM5160PWPR and LM5017MMX/NOPB, LM5161PWPT uniquely combines 100-V operation, 1-A capability, FPWM-selectable conduction mode, and full integration - making it the only option supporting robust Fly-Buck™ designs across industrial, telecom, and energy metering applications.
Availability
LM5161PWPT is available at Aetrix Electronics and suitable for industrial PLC power supplies, IGBT gate drive bias generation, and telecom DC-DC primary-side bias applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM5161PWPT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies with over 90 years of innovation in high-reliability power conversion solutions.
The LM5161 product line delivers wide-input, high-voltage synchronous buck/Fly-Buck™ controllers targeting industrial automation, telecom infrastructure, and smart energy systems where robustness, integration, and isolation capability are critical.
FAQ
What is the maximum input voltage supported by the LM5161PWPT?
The LM5161PWPT supports an absolute maximum input voltage of 100 V and a recommended operating range of 4.5 V to 100 V. This allows direct interface with 24 V, 48 V, and 72 V industrial and telecom buses, including transient surges common in PLC and PoE applications. Operation above 100 V risks permanent damage per absolute maximum ratings.
Does the LM5161PWPT require external compensation components?
No, the LM5161PWPT does not require external compensation components due to its constant ON-time control architecture. The internal error amplifier and soft-start capacitor (CSS) provide inherent loop stability across all operating conditions. This eliminates the need for external Type-II or Type-III compensation networks, reducing design complexity and component count.
How does the FPWM pin affect operation of the LM5161PWPT?
The FPWM pin on the LM5161PWPT selects conduction mode: grounding enables discontinuous conduction mode (DCM) for improved light-load efficiency, while connecting to VCC forces continuous conduction mode (CCM) for stable multi-output Fly-Buck™ operation. In CCM, the inductor current never reaches zero, enabling tighter regulation and predictable frequency behavior across load range.
Can the LM5161PWPT be used in Fly-Buck™ topology without optical feedback?
Yes, the LM5161PWPT supports Fly-Buck™ operation in forced CCM (FPWM = VCC) without optical feedback or secondary-side sensing. Its constant ON-time control and integrated synchronous rectifier enable tightly regulated isolated outputs using only primary-side components - verified in TI reference designs like TIDA-00781 for 12-V/5-V dual-output isolation.
What thermal considerations apply to the LM5161PWPT in high-input-voltage applications?
In high-input-voltage applications (e.g., 72–100 V), the internal VCC linear regulator dissipates significant power. To maintain thermal reliability, TI recommends externally biasing the VCC pin with 9–13 V from the output rail or auxiliary supply. This disables the internal regulator, reduces junction temperature, and improves overall efficiency - especially critical for continuous 1-A operation at elevated ambient temperatures.
LM5161PWPT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Buck, Flyback
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 100V
- Voltage - Output (Min/Fixed):
- 2V
- Voltage - Output (Max):
- 92V
- Current - Output:
- 1A
- Frequency - Switching:
- 50kHz ~ 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-HTSSOP
LM5161PWPT FAQ
1.How can I place an order for LM5161PWPT through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5161PWPT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM5161PWPT reliable?
The price and inventory of LM5161PWPT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5161PWPT is usually 5 days.
3.What payment methods are accepted for LM5161PWPT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5161PWPT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5161PWPT?
LM5161PWPT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5161PWPT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM5161PWPT?
For technical support, including LM5161PWPT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5161PWPT requirements.
6.How does Aetrix verify that LM5161PWPT is sourced from the original manufacturer or authorized distributors?
All LM5161PWPT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM5161PWPT meets industry standards.
7.What is the process for return or replacement of LM5161PWPT?
All LM5161PWPT units undergo pre-shipment inspection (PSI). If there is an issue with LM5161PWPT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM5161PWPT part is unused and in its original packaging.
Return procedure for LM5161PWPT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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